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From Mark Thomas <ma...@apache.org>
Subject Re: Headstart on "Resolving OOM-PermGen errors on webapp reload"
Date Tue, 21 Apr 2009 22:32:11 GMT
Ken Bowen wrote:
> Hey Mark,
> 
> This is really good.
> Presumably this is an outline for success 
It has a 100% success rate so far on a admittedly small sample size of
around 5 (I can't remember the exact number).

Mark

>-- and it is definitely an
> outline for improvement of my rather improvished skills in this area.
> Many thanks!
> 
> Ken
> 
> On Apr 21, 2009, at 5:54 PM, Mark Thomas wrote:
> 
>> Ken Bowen wrote:
>>> Mark,
>>>
>>> Any chance we could make a headstart on "Resolving OOM-PermGen errors on
>>> webapp reload" ??
>>> Perhaps some general pointers, guidance etc. [to help you refine the
>>> talk in advance :-) ]
>>
>> The very short version.
>>
>> 1. Find an app that you can't reload without OOME
>> 2. Get a profiler - I like Yourkit
>>   Full disclosure: they give ASF committers a free copy
>> 3. Reload you app once
>> 4. Use the profiler to look for instances of WebappClassLoader
>> 5. Look for the one with the started attribute == false
>> 6. Trace the GC roots for this instance
>> 7. Fix whatever is hanging on to references to the instance - there
>> should not be any
>>
>> The session (assuming it goes ahead) will do a demo of the above and
>> expand on 7 in terms of typical culprits and possible workarounds. It
>> will also explain what is going on and why this happens.
>>
>> HTH,
>>
>> Mark
>>
>>
>>
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> 
> 
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